The present invention relates to a power connection apparatus for supplying a power to, for example, an illuminative lamp or the like in a showcase.
In general, a showcase or the like is provided with a power connection apparatus constituted of a power socket connected to the inside of a chamber of a main body and a power plug plugged in this power socket to supply a power to an illuminative lamp or the like. In a conventional power connection apparatus disclosed in, for example, Japanese Patent Application Laid-Open No. 11-273775 (the patent document), a power socket is provided with a recess portion in which an electrode portion is disposed. This electrode portion is provided with plug-in ports for a power source. A power plug comprises a main body and a cylindrical portion connected to an illuminative lamp or the like via a wiring line, and terminals are provided on a bottom portion inside the cylindrical portion. In consequence, the power plug is plugged in the electrode portion of the power socket by plugging the terminals of the power plug in the power source plug-in ports of the power socket.
When the power connection apparatus is used in a low temperature showcase, the power plug serves for each of illuminative lamps and the like provided under front ends of a plurality of shelf devices arranged in the chamber. In the case of layout change or the like in the chamber, the arrangement positions of the shelf devices are changed, and accordingly, the power socket to be connected to the power plug is changed.
On the other hand, when the power connection apparatus is provided on a back surface in the chamber which becomes a low temperature in the showcase, humidity generated in the chamber easily invades each connecting portion between the electrode portion and each terminal. The invasion of the humidity causes electrical leakage or incurs the rusting of the terminals and the like. Moreover, frost is generated between the power plug and the power socket, which causes a problem that with the growth of the frost, a force is applied in a direction in which the power plug is detached from the power socket, and the power plug drops down.
To solve the problem, a preventive structure is employed in the connecting portion between the power plug and the power socket. However, this obstructs the attachment/detachment operation of the power plug and the power socket. Furthermore, in a low temperature environment, air in the power socket contracts, and hence the attachment/detachment operation further becomes difficult.
Therefore, to secure the connection between the power plug and the power socket, there has heretofore been developed a constitution in which engagement portions are provided on a power socket side, a handle rotatable at one end thereof is provided on a power plug side, and the handle has the other end provided with engaging claws disengageably engaged with the engagement portions on the power socket side.
In the above conventional constitution, even when the engaging claws of the power plug are not engaged with the engagement portions of the power socket in a state where the power plug is pressed onto the power socket, the terminals of the power plug have been brought into contact with the electrode portion of the power socket. Therefore, an operator discontinues the connection between the power plug and the power socket sometimes while keeping the state where the power plug is pressed onto the power socket and the engaging claws are not engaged with the engagement portions.
Even in this case, the terminals come in contact with the electrode portion, and hence the power is supplied to the illuminative lamp or the like provided with the power plug. However, when the power plug is left to stand in this state, the power plug easily drops down from the power socket, and in addition to the discontinuance of the power supply to the illuminative lamp or the like, water sticks to the terminals of the power plug or the electrode portion of the socket owing to the humidity in the chamber, which has been the cause for the electrical leakage or the rusting.
The present invention has been developed to solve the conventional technical problem, and an object thereof is to provide a power connection apparatus which can secure connection between a power socket and a power plug with a simple constitution and which can simplify the connecting operation properties thereof.